/****************************************************************************
 *
 * ftmm.h
 *
 *   FreeType Multiple Master font interface (specification).
 *
 * Copyright (C) 1996-2019 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */

#ifndef FTMM_H_
#define FTMM_H_

#include <ft2build.h>
#include FT_TYPE1_TABLES_H

FT_BEGIN_HEADER

/**************************************************************************
 *
 * @section:
 *   multiple_masters
 *
 * @title:
 *   Multiple Masters
 *
 * @abstract:
 *   How to manage Multiple Masters fonts.
 *
 * @description:
 *   The following types and functions are used to manage Multiple Master
 *   fonts, i.e., the selection of specific design instances by setting
 *   design axis coordinates.
 *
 *   Besides Adobe MM fonts, the interface supports Apple's TrueType GX and
 *   OpenType variation fonts.  Some of the routines only work with Adobe
 *   MM fonts, others will work with all three types.  They are similar
 *   enough that a consistent interface makes sense.
 *
 */

/**************************************************************************
 *
 * @struct:
 *   FT_MM_Axis
 *
 * @description:
 *   A structure to model a given axis in design space for Multiple Masters
 *   fonts.
 *
 *   This structure can't be used for TrueType GX or OpenType variation
 *   fonts.
 *
 * @fields:
 *   name ::
 *     The axis's name.
 *
 *   minimum ::
 *     The axis's minimum design coordinate.
 *
 *   maximum ::
 *     The axis's maximum design coordinate.
 */
typedef struct FT_MM_Axis_ {
	FT_String *name;
	FT_Long minimum;
	FT_Long maximum;

} FT_MM_Axis;

/**************************************************************************
 *
 * @struct:
 *   FT_Multi_Master
 *
 * @description:
 *   A structure to model the axes and space of a Multiple Masters font.
 *
 *   This structure can't be used for TrueType GX or OpenType variation
 *   fonts.
 *
 * @fields:
 *   num_axis ::
 *     Number of axes.  Cannot exceed~4.
 *
 *   num_designs ::
 *     Number of designs; should be normally 2^num_axis even though the
 *     Type~1 specification strangely allows for intermediate designs to be
 *     present.  This number cannot exceed~16.
 *
 *   axis ::
 *     A table of axis descriptors.
 */
typedef struct FT_Multi_Master_ {
	FT_UInt num_axis;
	FT_UInt num_designs;
	FT_MM_Axis axis[T1_MAX_MM_AXIS];

} FT_Multi_Master;

/**************************************************************************
 *
 * @struct:
 *   FT_Var_Axis
 *
 * @description:
 *   A structure to model a given axis in design space for Multiple
 *   Masters, TrueType GX, and OpenType variation fonts.
 *
 * @fields:
 *   name ::
 *     The axis's name.  Not always meaningful for TrueType GX or OpenType
 *     variation fonts.
 *
 *   minimum ::
 *     The axis's minimum design coordinate.
 *
 *   def ::
 *     The axis's default design coordinate.  FreeType computes meaningful
 *     default values for Adobe MM fonts.
 *
 *   maximum ::
 *     The axis's maximum design coordinate.
 *
 *   tag ::
 *     The axis's tag (the equivalent to 'name' for TrueType GX and
 *     OpenType variation fonts).  FreeType provides default values for
 *     Adobe MM fonts if possible.
 *
 *   strid ::
 *     The axis name entry in the font's 'name' table.  This is another
 *     (and often better) version of the 'name' field for TrueType GX or
 *     OpenType variation fonts.  Not meaningful for Adobe MM fonts.
 *
 * @note:
 *   The fields `minimum`, `def`, and `maximum` are 16.16 fractional values
 *   for TrueType GX and OpenType variation fonts.  For Adobe MM fonts, the
 *   values are integers.
 */
typedef struct FT_Var_Axis_ {
	FT_String *name;

	FT_Fixed minimum;
	FT_Fixed def;
	FT_Fixed maximum;

	FT_ULong tag;
	FT_UInt strid;

} FT_Var_Axis;

/**************************************************************************
 *
 * @struct:
 *   FT_Var_Named_Style
 *
 * @description:
 *   A structure to model a named instance in a TrueType GX or OpenType
 *   variation font.
 *
 *   This structure can't be used for Adobe MM fonts.
 *
 * @fields:
 *   coords ::
 *     The design coordinates for this instance.  This is an array with one
 *     entry for each axis.
 *
 *   strid ::
 *     The entry in 'name' table identifying this instance.
 *
 *   psid ::
 *     The entry in 'name' table identifying a PostScript name for this
 *     instance.  Value 0xFFFF indicates a missing entry.
 */
typedef struct FT_Var_Named_Style_ {
	FT_Fixed *coords;
	FT_UInt strid;
	FT_UInt psid; /* since 2.7.1 */

} FT_Var_Named_Style;

/**************************************************************************
 *
 * @struct:
 *   FT_MM_Var
 *
 * @description:
 *   A structure to model the axes and space of an Adobe MM, TrueType GX,
 *   or OpenType variation font.
 *
 *   Some fields are specific to one format and not to the others.
 *
 * @fields:
 *   num_axis ::
 *     The number of axes.  The maximum value is~4 for Adobe MM fonts; no
 *     limit in TrueType GX or OpenType variation fonts.
 *
 *   num_designs ::
 *     The number of designs; should be normally 2^num_axis for Adobe MM
 *     fonts.  Not meaningful for TrueType GX or OpenType variation fonts
 *     (where every glyph could have a different number of designs).
 *
 *   num_namedstyles ::
 *     The number of named styles; a 'named style' is a tuple of design
 *     coordinates that has a string ID (in the 'name' table) associated
 *     with it.  The font can tell the user that, for example,
 *     [Weight=1.5,Width=1.1] is 'Bold'.  Another name for 'named style' is
 *     'named instance'.
 *
 *     For Adobe Multiple Masters fonts, this value is always zero because
 *     the format does not support named styles.
 *
 *   axis ::
 *     An axis descriptor table.  TrueType GX and OpenType variation fonts
 *     contain slightly more data than Adobe MM fonts.  Memory management
 *     of this pointer is done internally by FreeType.
 *
 *   namedstyle ::
 *     A named style (instance) table.  Only meaningful for TrueType GX and
 *     OpenType variation fonts.  Memory management of this pointer is done
 *     internally by FreeType.
 */
typedef struct FT_MM_Var_ {
	FT_UInt num_axis;
	FT_UInt num_designs;
	FT_UInt num_namedstyles;
	FT_Var_Axis *axis;
	FT_Var_Named_Style *namedstyle;

} FT_MM_Var;

/**************************************************************************
 *
 * @function:
 *   FT_Get_Multi_Master
 *
 * @description:
 *   Retrieve a variation descriptor of a given Adobe MM font.
 *
 *   This function can't be used with TrueType GX or OpenType variation
 *   fonts.
 *
 * @input:
 *   face ::
 *     A handle to the source face.
 *
 * @output:
 *   amaster ::
 *     The Multiple Masters descriptor.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FT_Get_Multi_Master(FT_Face face, FT_Multi_Master *amaster);

/**************************************************************************
 *
 * @function:
 *   FT_Get_MM_Var
 *
 * @description:
 *   Retrieve a variation descriptor for a given font.
 *
 *   This function works with all supported variation formats.
 *
 * @input:
 *   face ::
 *     A handle to the source face.
 *
 * @output:
 *   amaster ::
 *     The variation descriptor.  Allocates a data structure, which the
 *     user must deallocate with a call to @FT_Done_MM_Var after use.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FT_Get_MM_Var(FT_Face face, FT_MM_Var **amaster);

/**************************************************************************
 *
 * @function:
 *   FT_Done_MM_Var
 *
 * @description:
 *   Free the memory allocated by @FT_Get_MM_Var.
 *
 * @input:
 *   library ::
 *     A handle of the face's parent library object that was used in the
 *     call to @FT_Get_MM_Var to create `amaster`.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FT_Done_MM_Var(FT_Library library, FT_MM_Var *amaster);

/**************************************************************************
 *
 * @function:
 *   FT_Set_MM_Design_Coordinates
 *
 * @description:
 *   For Adobe MM fonts, choose an interpolated font design through design
 *   coordinates.
 *
 *   This function can't be used with TrueType GX or OpenType variation
 *   fonts.
 *
 * @inout:
 *   face ::
 *     A handle to the source face.
 *
 * @input:
 *   num_coords ::
 *     The number of available design coordinates.  If it is larger than
 *     the number of axes, ignore the excess values.  If it is smaller than
 *     the number of axes, use default values for the remaining axes.
 *
 *   coords ::
 *     An array of design coordinates.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   [Since 2.8.1] To reset all axes to the default values, call the
 *   function with `num_coords` set to zero and `coords` set to `NULL`.
 *
 *   [Since 2.9] If `num_coords` is larger than zero, this function sets
 *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
 *   (i.e., @FT_IS_VARIATION will return true).  If `num_coords` is zero,
 *   this bit flag gets unset.
 */
FT_EXPORT(FT_Error)
FT_Set_MM_Design_Coordinates(FT_Face face, FT_UInt num_coords, FT_Long *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Set_Var_Design_Coordinates
 *
 * @description:
 *   Choose an interpolated font design through design coordinates.
 *
 *   This function works with all supported variation formats.
 *
 * @inout:
 *   face ::
 *     A handle to the source face.
 *
 * @input:
 *   num_coords ::
 *     The number of available design coordinates.  If it is larger than
 *     the number of axes, ignore the excess values.  If it is smaller than
 *     the number of axes, use default values for the remaining axes.
 *
 *   coords ::
 *     An array of design coordinates.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   [Since 2.8.1] To reset all axes to the default values, call the
 *   function with `num_coords` set to zero and `coords` set to `NULL`.
 *   [Since 2.9] 'Default values' means the currently selected named
 *   instance (or the base font if no named instance is selected).
 *
 *   [Since 2.9] If `num_coords` is larger than zero, this function sets
 *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
 *   (i.e., @FT_IS_VARIATION will return true).  If `num_coords` is zero,
 *   this bit flag gets unset.
 */
FT_EXPORT(FT_Error)
FT_Set_Var_Design_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Get_Var_Design_Coordinates
 *
 * @description:
 *   Get the design coordinates of the currently selected interpolated
 *   font.
 *
 *   This function works with all supported variation formats.
 *
 * @input:
 *   face ::
 *     A handle to the source face.
 *
 *   num_coords ::
 *     The number of design coordinates to retrieve.  If it is larger than
 *     the number of axes, set the excess values to~0.
 *
 * @output:
 *   coords ::
 *     The design coordinates array.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @since:
 *   2.7.1
 */
FT_EXPORT(FT_Error)
FT_Get_Var_Design_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Set_MM_Blend_Coordinates
 *
 * @description:
 *   Choose an interpolated font design through normalized blend
 *   coordinates.
 *
 *   This function works with all supported variation formats.
 *
 * @inout:
 *   face ::
 *     A handle to the source face.
 *
 * @input:
 *   num_coords ::
 *     The number of available design coordinates.  If it is larger than
 *     the number of axes, ignore the excess values.  If it is smaller than
 *     the number of axes, use default values for the remaining axes.
 *
 *   coords ::
 *     The design coordinates array (each element must be between 0 and 1.0
 *     for Adobe MM fonts, and between -1.0 and 1.0 for TrueType GX and
 *     OpenType variation fonts).
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   [Since 2.8.1] To reset all axes to the default values, call the
 *   function with `num_coords` set to zero and `coords` set to `NULL`.
 *   [Since 2.9] 'Default values' means the currently selected named
 *   instance (or the base font if no named instance is selected).
 *
 *   [Since 2.9] If `num_coords` is larger than zero, this function sets
 *   the @FT_FACE_FLAG_VARIATION bit in @FT_Face's `face_flags` field
 *   (i.e., @FT_IS_VARIATION will return true).  If `num_coords` is zero,
 *   this bit flag gets unset.
 */
FT_EXPORT(FT_Error)
FT_Set_MM_Blend_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Get_MM_Blend_Coordinates
 *
 * @description:
 *   Get the normalized blend coordinates of the currently selected
 *   interpolated font.
 *
 *   This function works with all supported variation formats.
 *
 * @input:
 *   face ::
 *     A handle to the source face.
 *
 *   num_coords ::
 *     The number of normalized blend coordinates to retrieve.  If it is
 *     larger than the number of axes, set the excess values to~0.5 for
 *     Adobe MM fonts, and to~0 for TrueType GX and OpenType variation
 *     fonts.
 *
 * @output:
 *   coords ::
 *     The normalized blend coordinates array.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @since:
 *   2.7.1
 */
FT_EXPORT(FT_Error)
FT_Get_MM_Blend_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Set_Var_Blend_Coordinates
 *
 * @description:
 *   This is another name of @FT_Set_MM_Blend_Coordinates.
 */
FT_EXPORT(FT_Error)
FT_Set_Var_Blend_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Get_Var_Blend_Coordinates
 *
 * @description:
 *   This is another name of @FT_Get_MM_Blend_Coordinates.
 *
 * @since:
 *   2.7.1
 */
FT_EXPORT(FT_Error)
FT_Get_Var_Blend_Coordinates(FT_Face face, FT_UInt num_coords, FT_Fixed *coords);

/**************************************************************************
 *
 * @function:
 *   FT_Set_MM_WeightVector
 *
 * @description:
 *   For Adobe MM fonts, choose an interpolated font design by directly
 *   setting the weight vector.
 *
 *   This function can't be used with TrueType GX or OpenType variation
 *   fonts.
 *
 * @inout:
 *   face ::
 *     A handle to the source face.
 *
 * @input:
 *   len ::
 *     The length of the weight vector array.  If it is larger than the
 *     number of designs, the extra values are ignored.  If it is less than
 *     the number of designs, the remaining values are set to zero.
 *
 *   weightvector ::
 *     An array representing the weight vector.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   Adobe Multiple Master fonts limit the number of designs, and thus the
 *   length of the weight vector to~16.
 *
 *   If `len` is zero and `weightvector` is `NULL`, the weight vector array
 *   is reset to the default values.
 *
 *   The Adobe documentation also states that the values in the
 *   WeightVector array must total 1.0 +/-~0.001.  In practice this does
 *   not seem to be enforced, so is not enforced here, either.
 *
 * @since:
 *   2.10
 */
FT_EXPORT(FT_Error)
FT_Set_MM_WeightVector(FT_Face face, FT_UInt len, FT_Fixed *weightvector);

/**************************************************************************
 *
 * @function:
 *   FT_Get_MM_WeightVector
 *
 * @description:
 *   For Adobe MM fonts, retrieve the current weight vector of the font.
 *
 *   This function can't be used with TrueType GX or OpenType variation
 *   fonts.
 *
 * @inout:
 *   face ::
 *     A handle to the source face.
 *
 *   len ::
 *     A pointer to the size of the array to be filled.  If the size of the
 *     array is less than the number of designs, `FT_Err_Invalid_Argument`
 *     is returned, and `len` is set to the required size (the number of
 *     designs).  If the size of the array is greater than the number of
 *     designs, the remaining entries are set to~0.  On successful
 *     completion, `len` is set to the number of designs (i.e., the number
 *     of values written to the array).
 *
 * @output:
 *   weightvector ::
 *     An array to be filled.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   Adobe Multiple Master fonts limit the number of designs, and thus the
 *   length of the WeightVector to~16.
 *
 * @since:
 *   2.10
 */
FT_EXPORT(FT_Error)
FT_Get_MM_WeightVector(FT_Face face, FT_UInt *len, FT_Fixed *weightvector);

/**************************************************************************
 *
 * @enum:
 *   FT_VAR_AXIS_FLAG_XXX
 *
 * @description:
 *   A list of bit flags used in the return value of
 *   @FT_Get_Var_Axis_Flags.
 *
 * @values:
 *   FT_VAR_AXIS_FLAG_HIDDEN ::
 *     The variation axis should not be exposed to user interfaces.
 *
 * @since:
 *   2.8.1
 */
#define FT_VAR_AXIS_FLAG_HIDDEN 1

/**************************************************************************
 *
 * @function:
 *   FT_Get_Var_Axis_Flags
 *
 * @description:
 *   Get the 'flags' field of an OpenType Variation Axis Record.
 *
 *   Not meaningful for Adobe MM fonts (`*flags` is always zero).
 *
 * @input:
 *   master ::
 *     The variation descriptor.
 *
 *   axis_index ::
 *     The index of the requested variation axis.
 *
 * @output:
 *   flags ::
 *     The 'flags' field.  See @FT_VAR_AXIS_FLAG_XXX for possible values.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @since:
 *   2.8.1
 */
FT_EXPORT(FT_Error)
FT_Get_Var_Axis_Flags(FT_MM_Var *master, FT_UInt axis_index, FT_UInt *flags);

/**************************************************************************
 *
 * @function:
 *   FT_Set_Named_Instance
 *
 * @description:
 *   Set or change the current named instance.
 *
 * @input:
 *   face ::
 *     A handle to the source face.
 *
 *   instance_index ::
 *     The index of the requested instance, starting with value 1.  If set
 *     to value 0, FreeType switches to font access without a named
 *     instance.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The function uses the value of `instance_index` to set bits 16-30 of
 *   the face's `face_index` field.  It also resets any variation applied
 *   to the font, and the @FT_FACE_FLAG_VARIATION bit of the face's
 *   `face_flags` field gets reset to zero (i.e., @FT_IS_VARIATION will
 *   return false).
 *
 *   For Adobe MM fonts (which don't have named instances) this function
 *   simply resets the current face to the default instance.
 *
 * @since:
 *   2.9
 */
FT_EXPORT(FT_Error)
FT_Set_Named_Instance(FT_Face face, FT_UInt instance_index);

/* */

FT_END_HEADER

#endif /* FTMM_H_ */

/* END */
